//
//  SQLiteDataBaseManager.m
//  18-SQLite
//
//  Created by 曹曹 on 16/8/8.
//  Copyright © 2016年 曹曹. All rights reserved.
//

#import "SQLiteDataBaseManager.h"
#import "Student.h"

@implementation SQLiteDataBaseManager
#pragma mark - 单例创建方式, 只有一个对象
// 内存管理中,单例不能被释放(不要去release)
+ (SQLiteDataBaseManager *)sharedManager {
    static SQLiteDataBaseManager *manager = nil;
    // 保证线程安全, 只执行一次
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        manager = [[SQLiteDataBaseManager alloc] init];
    });
    return manager;
}
#pragma mark - open
- (BOOL)openSQLite {
    NSArray *pathArray = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
    NSString *documentPath = [pathArray firstObject];
    // 数据库sqlite3文件类型(.db)
    NSString *dbPath = [documentPath stringByAppendingPathComponent:@"student.db"];
    NSLog(@"dbPath:%@", dbPath);
    // UTF8String属性, 将OC字符串转换成C语言字符串
    // 参数1:数据库文件路径
    // 参数2:指向指针的指针, 该指针可以被修改, 数据库管理指针
    int result = sqlite3_open(dbPath.UTF8String, &dbPointer);
    // sqlite3_open 当路径文件不存在时, 文件会被sqlite3创建并打开
    // 当路径文件存在时, 文件被直接打开
    // sqlite3_open返回值为int型,0(SQLITE_OK)代表成功, 1代表失败(枚举)
    return [self isOperationResult:result alertText:@"打开"];
}
#pragma mark - close
- (BOOL)closeSQLite {
    // 关闭数据库时, 如果数据库处于打开状态, 则数据库正常关闭, 显示成功
    // 如果数据库处于关闭状态, 则显示失败, 错误码21,库不存在
    int result = sqlite3_close(dbPointer);
    return [self isOperationResult:result alertText:@"关闭"];
}
#pragma mark - create table
- (BOOL)createTable {
    // SQL语句
    // 创建表
    // create table 表名(字段1 约束, 字段2, 字段3, ...)
//    NSString *createSQL = @"create table stu(stu_id integer primary key, stu_name text)";
//    NSString *createSQL = @"create table stu1(stu_id integer primary key autoincrement, stu_name text)";
    // 常用的约束
    // primary key 一个表, 有且只能有一个主键
    // autoincreatement 自增, 添加完该字段, 系统会自己创建一个数据库的表sqlite_sequence, 用来保存自增的值
    // not null 不能为空, 为空会报SQL错误
    // 删除表
    // SQL语句drop table 表名
    NSString *createSQL = @"create table stu2(stu_id integer primary key autoincrement, stu_name text not null)";
    int result = sqlite3_exec(dbPointer, createSQL.UTF8String, NULL, NULL, NULL);
    return [self isOperationResult:result alertText:@"创建表"];
}
#pragma mark - insert
- (BOOL)insertStu:(Student *)stu {
    NSString *insertSQL = [NSString stringWithFormat:@"insert into stu1 values (null, '%@')", stu.stu_name];
    // 自增字段, autoincrement
    // 默认如果填入null, 值会从1开始
    // 如果填入其他值, 会从其他值开始, 例:填入110,值从110开始计算, 并进行存贮, 存储在sqlite_sequence表里
    //NSString *insertSQL = @"insert into stu1 (stu_id, stu_name) values (null, '小宝')";
    int result = sqlite3_exec(dbPointer, insertSQL.UTF8String, NULL, NULL, NULL);
    return [self isOperationResult:result alertText:@"插入数据"];
}
#pragma mark - delete
- (BOOL)deleteStu:(Student *)stu {
    NSString *deleteSQL = [NSString stringWithFormat:@"delete from stu1 where stu_id = %ld", stu.stu_id];
    int result = sqlite3_exec(dbPointer, deleteSQL.UTF8String, NULL, NULL, NULL);
    NSString *alertText = [NSString stringWithFormat:@"删除学号为%ld的一条数据", stu.stu_id];
    return [self isOperationResult:result alertText:alertText];;
}
#pragma mark - deleteAll
- (BOOL)deleteAll {
    NSString *deleteSQL = @"delete from stu1 where 1 = 1";
    int result = sqlite3_exec(dbPointer, deleteSQL.UTF8String, NULL, NULL, NULL);
    return [self isOperationResult:result alertText:@"删除全部数据"];;
}
#pragma mark - update
- (BOOL)updateOldName:(NSString *)oldName
              newName:(NSString *)newName {
    // update 表名 set 字段名 = 新值 where 字段名 = 旧值
    NSString *updateSQL = [NSString stringWithFormat:@"update stu1 set stu_name = '%@' where stu_name = '%@'", newName, oldName];
    int result = sqlite3_exec(dbPointer, updateSQL.UTF8String, NULL, NULL, NULL);
    return [self isOperationResult:result alertText:@"更新"];;
}
#pragma mark - query
- (NSArray *)selectAll {
    // select 字段名, 字段名, ...(*表示查询所有) from 表名 where 条件
    NSString *selectAll = @"select * from stu1";
    // 替身指针
    sqlite3_stmt *stmt = NULL;
    // 参数1: 数据库指针
    // 参数2: SQL语句
    // 参数3: SQL语句的长度, 一般填 -1(不限制长度)
    // 参数4: 替身, 查询出的内容放入替身中, 并将替身返回
    int result = sqlite3_prepare(dbPointer, selectAll.UTF8String, -1, &stmt, NULL);
    NSMutableArray *stuArray = [NSMutableArray array];
    // 如果查询结果为成功
    if (result == SQLITE_OK) {
        // 循环, 遍历替身内容
        // step会查询替身中有没有其他数据
        // 当包含有其他数据时, 结果为SQLITE_ROW
        // 当不包含其他数据时, 结果为SQLITE_DONE
        while (sqlite3_step(stmt) == SQLITE_ROW) {
            // 循环体中, 取对应每一列数据
            // 取出第0列的数据, 根据类型选择函数 int
            int stu_id = sqlite3_column_int(stmt, 0);
            // 取出第1列的数据, 根据类型选择函数 text
            const unsigned char *stu_name = sqlite3_column_text(stmt, 1);
            Student *stu = [[Student alloc] init];
            stu.stu_id = stu_id;
            stu.stu_name = [NSString stringWithUTF8String:(const char *)stu_name];
            [stuArray addObject:stu];
        }
    }
    // 循环结束处理完数据后, 销毁替身
    sqlite3_finalize(stmt);
    return stuArray;
}
- (BOOL)isOperationResult:(int)result alertText:(NSString *)text {
    BOOL isOperation = YES;
    if (result == SQLITE_OK) {
        NSLog(@"数据库%@成功", text);
        isOperation = YES;
    } else {
        NSLog(@"数据库%@失败----错误码:%d", text, result);
        isOperation = NO;
    }
    return isOperation;
}


@end
